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Finding the Fourth Proportional to 78.19, 117.43 and 66.69

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Solution

The fourth proportional to 78.19, 117.43 and 66.69 is: 100.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.19 : 117.43 = 66.69 : x
  2. Step 2: Convert to fraction form
    78.19/117.43 = 66.69/x
  3. Step 3: Cross multiply
    78.19x = 117.43 × 66.69
  4. Step 4: Simplify right side
    78.19x = 7,831.41
  5. Step 5: Solve for x
    x = 7,831.41/78.19
  6. Step 6: Final answer
    x = 100.16

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.